1. Field of the Invention
The invention relates generally to hydraulic switches used to control the actuation of multiple pressure controlled devices within a wellbore.
2. Description of the Related Art
It is common in downhole wellbore production systems to employ sliding sleeve valves, safety valve or chemical injection valves that use hydraulic pressure control for actuation. Each of these pressure controlled devices (“PCD”s) uses a pair of hydraulic control lines—an inflow line and an outflow line. In a number of instances, it is desired to have multiple PCDs within a borehole. Because each PCD uses two control lines, this means that a large number of control lines that must be run into the wellbore. The inventor has realized that there are a number of significant advantages to being able to reduce the number of control lines that are run into a wellbore. The reduction of control lines results in a direct reduction in cost due to the reduced amount of control line that must be run into the wellbore. In addition, there are indirect savings, particularly in deepwater wells, as there are fewer lines that require a dedicated feed through in the subsea tree and dedicated umbilicals back to the surface. Moreover, each additional control line that is used in a wellbore requires dedicated pressure testing and time. Further, a reduced number of control lines results in a more reliable system since the number of potential leak paths is reduced.